xfs: kill b_file_offset

Seeing as we pass block numbers around everywhere in the buffer
cache now, it makes no sense to index everything by byte offset.
Replace all the byte offset indexing with block number based
indexing, and replace all uses of the byte offset with direct
conversion from the block index.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 7 insertions, 10 deletions

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index d3a1974c91d..854b27a8e77 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -196,7 +196,7 @@ xfs_buf_alloc(
         sema_init(&bp->b_sema, 0); /* held, no waiters */
         XB_SET_OWNER(bp);
         bp->b_target = target;
-        bp->b_file_offset = blkno << BBSHIFT;
+
         /*
          * Set buffer_length and count_desired to the same value initially.
          * I/O routines should use count_desired, which will be the same in
@@ -337,8 +337,8 @@ xfs_buf_allocate_memory(
         }
 
 use_alloc_page:
-        end = bp->b_file_offset + bp->b_buffer_length;
-        page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
+        end = BBTOB(bp->b_bn) + bp->b_buffer_length;
+        page_count = xfs_buf_btoc(end) - xfs_buf_btoct(BBTOB(bp->b_bn));
         error = _xfs_buf_get_pages(bp, page_count, flags);
         if (unlikely(error))
                 return error;
@@ -439,19 +439,17 @@ _xfs_buf_find(
         xfs_buf_flags_t         flags,
         xfs_buf_t               *new_bp)
 {
-        xfs_off_t               offset;
         size_t                  numbytes;
         struct xfs_perag        *pag;
         struct rb_node          **rbp;
         struct rb_node          *parent;
         xfs_buf_t               *bp;
 
-        offset = BBTOB(blkno);
         numbytes = BBTOB(numblks);
 
         /* Check for IOs smaller than the sector size / not sector aligned */
         ASSERT(!(numbytes < (1 << btp->bt_sshift)));
-        ASSERT(!(offset & (xfs_off_t)btp->bt_smask));
+        ASSERT(!(BBTOB(blkno) & (xfs_off_t)btp->bt_smask));
 
         /* get tree root */
         pag = xfs_perag_get(btp->bt_mount,
@@ -466,13 +464,13 @@ _xfs_buf_find(
                 parent = *rbp;
                 bp = rb_entry(parent, struct xfs_buf, b_rbnode);
 
-                if (offset < bp->b_file_offset)
+                if (blkno < bp->b_bn)
                         rbp = &(*rbp)->rb_left;
-                else if (offset > bp->b_file_offset)
+                else if (blkno > bp->b_bn)
                         rbp = &(*rbp)->rb_right;
                 else {
                         /*
-                         * found a block offset match. If the range doesn't
+                         * found a block number match. If the range doesn't
                          * match, the only way this is allowed is if the buffer
                          * in the cache is stale and the transaction that made
                          * it stale has not yet committed. i.e. we are
@@ -718,7 +716,6 @@ xfs_buf_set_empty(
         bp->b_pages = NULL;
         bp->b_page_count = 0;
         bp->b_addr = NULL;
-        bp->b_file_offset = 0;
         bp->b_buffer_length = bp->b_count_desired = numblks << BBSHIFT;
         bp->b_bn = XFS_BUF_DADDR_NULL;
         bp->b_flags &= ~XBF_MAPPED;